Dense wavelength division multiplexing (DWDM) technology is a dominant technology in long-distance and area trunk transmission networks and gradually comes into metropolitan area networks. Traditional DWDM systems use independent device packages in which cards are made surrounding one or more optical devices and connected through optical fibers.
Prices of optical devices fall constantly as technology advances. Up to now, only costs of encapsulating optical devices are still high and become a bottle neck constraining optical device costs. As a typical example, a core of laser only costs several dollars while its package will cost hundreds of dollars.
In recent years, efforts have been made to integrate multiple optical devices such as lasers and modulators into a single semiconductor substrate so as to reduce cost of packaging an optical device separately. Meanwhile, a smaller package also enables the volumes of submodules in a DWDM system such as transmitting, receiving and monitoring submodules to substantially decrease.
An optoelectronic integrated circuit is a circuit that integrates multiple optical devices in a common semiconductor substrate with corresponding peripheral control circuits. FIG. 1 is a diagram showing internal structure of an integrated optoelectronic device at a transmitting end in the prior art. Referring to FIG. 1, for achieving information transmission by optoelectronic integrated circuit, in the conventional art, the transmitting-end integrated optoelectronic device includes therein a high-level control unit, a data exchange unit, a light source link control unit, n light source links and their corresponding n data channels as well as a wavelength multiplexed unit. FIG. 2 is a diagram showing a transmitting end in the prior art, in which data transmission is performed by data channels and light source links. Referring to FIGS. 1 and 2, in practical service implementations, each light source link mainly includes a light source and a modulator and may further include a light path tap module. The link detecting circuit in light source link control unit detects performance of each light source link with the Tap module in each light source link, to enable the light source link control unit to properly adjust light source link according to detection results, such as adjusting optical power in the light source link. FIG. 3 is a diagram showing structure of an integrated optoelectronic device at a receiving end in prior art. Referring to FIG. 3, the receiving-end integrated optoelectronic device mainly includes therein a wavelength demultiplexed unit, n optical receiving units and an electronic data processing unit.
During information transmission, in the transmitting-end integrated optoelectronic device, the light source in the light source link generates optical signals and outputs the optical signals to the modulators. The corresponding data channels output electronic signals to the modulators that modulate the received optical signals and electronic signals to produce optical signals to be output to the wavelength multiplexed module. The wavelength multiplexed module multiplexes optical signals received from all light source links and outputs the multiplexed optical signals to the receiving-end integrated optoelectronic device. In the receiving-end integrated optoelectronic device, the wavelength demultiplexed unit demultiplexes the received optical signals and outputs the demultiplexed n paths of optical signals to corresponding optical receiving units. Each optical receiving unit converts the received optical signals into electronic signals and then outputs them to the electronic data processing unit for corresponding processing.
At present, optical signals have advantages such as strong anti-jamming performance and fast transmission speed over electronic signals in terms of information transmission. Therefore, the integrated optoelectronic devices are widely applied.
However, there is no effective protective measure for integrated optoelectronic devices at present and each light source link would be used as an active link for practical service transmission. Thus, when any one of the light source links in an integrated optoelectronic device fails, for example, when the light source does not generate light or the modulator fails, the entire integrated optoelectronic device will malfunction, and the reliability of the integrated optoelectronic device is thereby decreased. One approach for curing such a malfunction in existing systems is to replace, the light source links of the integrated optoelectronic device. However, since the components of each light source link in the integrated optoelectronic device are integrated onto a single substrate in a single package, it is impossible to replace the failed light source link independently. Therefore, in the existing systems it is necessary to replace the entire optoelectronic integrated circuit when only an individual component fails, thereby significantly increasing maintenance and repair costs.